1. Field of the Invention
The invention relates to the field of power electronics. It is based on a power converter circuit arrangement according to the preamble of the first claim.
2. Discussion of Background
Such a power converter circuit arrangement is described for example in the article "Leistungsstarke statische Frequenzumrichter fur den Bahnverkehr durch die Alpen" [High-power static frequency converters for railway traffic through the Alps], ABB Technik 5/1996, pages 4-10, or in the article "Umrichterwerk Jubek" [Converter works Jubek], Elektrische Bahnen 93 (1995) 3, or in the article "Statischer Umrichter Muldenstein" [Static converter Muldenstein], Elektrische Bahnen 93 (1995) 1/2.
In principle, either the so-called two-point invertor or three-point invertor technology is used in the circuit arrangements according to the prior art. A plurality of power converter units having a transformer on the output side are provided, which transformer feeds a load circuit via a common or separate, load- or railway-side secondary winding. If the secondary windings are separate, they are connected in series.
With the designs according to the prior art, a finely stepped output voltage is achieved by a multiplicity of individual stages whose output voltages are added. The requisite GTOs, their circuitry and, in particular, the outlay for the transformers can considerably increase the production cost of the circuit arrangement.